Printing spares for fluid power systems

29 May 2026  

Additive manufacturing is beginning to play a practical role in keeping hydraulic and pneumatic systems running, particularly where parts are difficult to source and downtime is costly. H&P reports.

Keeping fluid power systems in service has always relied on the availability of replacement parts, but that assumption is becoming harder to sustain across much of UK industry. Installations in water, rail, energy and process sectors are often expected to operate well beyond their original design life, while the supply chains that once supported them have thinned out. When a hydraulic component fails, the difficulty is no longer just technical. In many cases, the part itself is no longer readily obtainable, or the lead time makes repair impractical within the demands of day-to-day operations.

In this environment, additive manufacturing is being used less as a development tool and more as a means of maintaining continuity. The technology is not replacing established production methods, nor is it being applied across the board. Its value lies in specific situations where a part cannot be sourced quickly enough and where the consequences of delay are significant. That tends to mean low-volume, application-specific components rather than standard catalogue items.

Hydraulic manifolds

Hydraulic manifolds are among the most frequently cited examples, and for good reason. Their internal geometry is often complex, with intersecting flow paths designed around a particular circuit layout. Traditional manufacture relies on drilling and plugging, or on casting followed by machining, both of which can involve long lead times when starting from scratch. When a manifold fails on an older installation, the original drawings may be incomplete or unavailable, and reproducing the part through conventional means can be slow and costly. Additive manufacturing provides an alternative route by allowing the geometry to be recreated from a physical sample and produced without dedicated tooling.

The practical benefit in this context is not simply speed, but the ability to avoid prolonged downtime. A processing line or pumping station held up by a single unavailable component can incur costs that quickly outweigh the price of the part itself. Where additive manufacturing can shorten the interruption from several weeks to a matter of days, it becomes a viable option even if the unit cost is higher than that of a traditionally manufactured replacement.

The same logic applies to valve bodies, actuator housings and various mounting or interface components that are specific to a particular system. Pneumatic equipment tends to operate at lower pressures, but the need for tailored fittings and brackets is common, especially in automated lines that have evolved over time. In both hydraulics and pneumatics, the parts that cause the greatest difficulty are often those that were never intended to be standardised in the first place.

Producing these components additively is not a straightforward copy-and-replace exercise. Reverse engineering requires a clear understanding of how the original part performs, particularly where sealing surfaces and pressure boundaries are involved. Hydraulic systems are unforgiving of poor tolerances or surface finish, and any deviation can lead to leakage, pressure loss or contamination issues. Decisions about material choice and post-processing therefore carry as much weight as the initial geometry. In some cases, the design is adjusted to suit the characteristics of the additive process, for example by smoothing internal flow paths or consolidating features that were previously assembled.

This introduces an important distinction between simply reproducing a part and improving it. There is an opportunity, when recreating a component, to address known issues such as sharp internal corners that contribute to pressure drop or areas where stress concentrations have led to repeated failure. While the primary aim in a maintenance scenario is to restore function, there is often scope to make incremental improvements without altering the overall behaviour of the system.

The way spare parts are managed is also starting to change. Rather than holding extensive physical inventories, some operators are identifying a subset of critical components and ensuring that accurate digital models exist for those items. These models are treated as production data, with defined materials and process parameters, rather than as simple drawings. When a part is required, it can be produced on demand either internally or through a specialist supplier. This approach reduces the need to carry rarely used stock while still providing a route to replacement when needed.

For UK operators, the appeal of this model has been reinforced by recent supply chain disruptions. Delays in international shipping and the reduced availability of certain components have highlighted the risks associated with relying entirely on external suppliers. Fluid power systems are particularly exposed because they often depend on a small number of critical parts. Additive manufacturing does not remove that dependency, but it does offer a degree of flexibility by enabling local production where appropriate.

Cost considerations

Cost considerations tend to be more complex than a simple comparison between manufacturing methods. Additive manufacturing is rarely the lowest-cost option in terms of the part alone, especially when compared with established processes operating at scale. However, maintenance decisions are influenced by the wider cost of downtime, including lost production, contractual penalties and the practical impact on operations. In that context, a more expensive component that restores service quickly may represent the better outcome.

Lead time remains a factor that needs to be managed carefully. Even with additive manufacturing, producing a part involves design work, build time and finishing operations. The most effective use of the technology comes when these steps have been considered in advance. Maintenance teams that have identified vulnerable components and prepared digital models are better placed to respond quickly than those attempting to start the process after a failure has occurred.

Material performance is another area where caution is required. Hydraulic components in particular are subject to high pressures and cyclic loading, which place demands on strength and fatigue resistance. Additive processes now support a range of metals suitable for many applications, but they do not yet replicate the full range of materials and treatments available through conventional routes. Each application needs to be assessed on its own merits, with appropriate testing and validation where necessary.

Quality assurance follows from this. Components produced for use in fluid power systems must meet the same expectations of reliability as those made by traditional methods. Inspection regimes, including dimensional checks and non-destructive testing, are increasingly being applied to additively manufactured parts. The level of scrutiny depends on the function of the component, but pressure-containing parts will always require a higher degree of verification.

Not every organisation is in a position to invest in its own additive manufacturing capability, and in many cases that is neither necessary nor desirable. A growing number of specialist providers offer services that cover the full process from design through to production and testing. For many UK companies, this provides access to the technology without the need for significant capital investment, while still allowing them to benefit from shorter lead times and greater flexibility.

It is important to recognise that additive manufacturing is not displacing traditional production methods in the context of spare parts. Casting, forging and machining remain the most effective approaches for standard components and for higher volumes. What is changing is the range of options available when those methods are not practical. Additive manufacturing fills a gap that has become more apparent as equipment ages and supply chains evolve.

The result is a more adaptable approach to maintenance. Instead of relying solely on what can be sourced externally, engineers have an additional route for addressing failures that would otherwise be difficult to resolve. This does not eliminate the need for planning or for careful engineering judgement, but it does provide a degree of control that was previously lacking.

For those responsible for hydraulic and pneumatic systems, the relevance of additive manufacturing lies in its ability to deal with the awkward cases rather than the routine ones. Where parts are standard and readily available, established supply chains continue to serve their purpose. Where they are not, the option to produce a replacement locally, within a controlled framework, is becoming increasingly valuable.